When you start a konsole and type the commands to start an application you
will see all sorts of statements are printed in the konsole while the
application is running. All applications print these messages, to look
at them you have to know where to look. The application will have to be
compiled with the debugging enabled. So using a precompiled package from a distribution
probably will not give you this information. If you compiled the application
yourself, make sure the configure option "--disable-debug" was not used.

In KDE all debugging text-output can be switched on or off based on so
called areas. One application can be one or more area. One part of the kde base libraries can be another area. Enabling/disabling these areas from being printed can be done using the kdebugdialog application. For simple debugging selecting all
sections is probably wise.

When you are debugging it is best to simply start a konsole and start the
application from there. In a konsole you could simply type:

kicker

and in the konsole kicker could return a message like:

ERROR: kicker is already running!

When a lot of output is written to the konsole it might go out of view before
you could read it, therefor it is easy to create a text file which contains
all this information, to do so type the following:

application 2>&1 | tee debug.log

where 'application' can be replaced with the application you are debugging.
Afterwards you could open the file 'debug.log' to look at the messages again.

If you are NOT starting the application from a konsole the messages will be
logged somewhere else, or they could have been discarded by the program that
started your application.

If your application is started by clicking on an icon your best bet is to check
the following log files. Beware; they contain logs for a lot of applications,
not just the application you are debugging!

Case 1: Graphical login (i.e. kdm, gdm, xdm, etc.

The debug messages get redirected into the file ~/.xsession-errors or
~/.X.err in your home directory (that is with a leading dot '.' also
watch the Capital).

Case 2: You are using startx:

Use the following command to restart your session:

startx 2>&1 | tee startx.log</pre>

so that all the debug messages of applications started at KDE's startup (and
any application launched from the panel etc.) go to the file "startx.log"

Links

The debug messages are usually printed in C++ with the kDebug or kWarning statement. Example: